Substrate plating method and apparatus

Abstract

A substrate plating method makes it possible to plate a metal, such as copper or a copper alloy, uniformly into fine recesses in a substrate without forming voids in the metal-filled recesses. The substrate plating method for filling a metal into fine recesses in a surface to be plated of a substrate includes carrying out first plating on the surface to be plated in a plating solution containing a plating accelerator as an additive, carrying out plating accelerator removal processing by bringing a remover, having the property of removing or decreasing the plating accelerator adsorbed on the plating surface, into contact with the plating surface, and then carrying out second plating on the plating surface at a constant electric potential.

1. A substrate plating method comprising:
 preparing a substrate having trenches or holes for use in three-dimensional packaging, the trenches or holes being formed in a surface of the substrate to be plated; 
 performing a first electroplating process on the surface of the substrate by immersing the substrate and a first anode in a first electrolytic solution containing a plating accelerator as an additive such that the substrate and the first anode face each other, and applying a voltage between the substrate serving as a cathode and the first anode, so that a plated metal film is formed on the surface to be plated of the substrate while allowing the plating accelerator to be adsorbed onto a plating surface of the plated metal film; 
 performing a plating accelerator removal process by immersing a cathode and the substrate with the plating surface into a second electrolytic solution containing a remover and without the plating accelerator such that the substrate and the cathode face each other, and applying a voltage between the substrate serving as an anode and the cathode, thereby removing the plating accelerator from an outer portion of the plating surface and areas of openings of the trenches or holes while leaving the plating accelerator in the deep portions of the trenches or holes; and then 
 performing a second electroplating process on the plating surface of the plated metal film at a constant electric potential by immersing the substrate and a second anode into a third electrolytic solution without the plating accelerator such that the substrate and the second anode face each other, and applying a voltage between the substrate serving as a cathode and the second anode. 
 
     
     
       2. The substrate plating method according to  claim 1 , wherein the plating accelerator comprises a sulfur compound. 
     
     
       3. The substrate plating method according to  claim 1 , wherein the remover removes the plating accelerator by competitive adsorption. 
     
     
       4. The substrate plating method according to  claim 3 , wherein the remover comprises chloride ions. 
     
     
       5. The substrate plating method according to  claim 1 , wherein said performing of the second electroplating process includes detecting a change in electric current during the second electroplating process;
 said substrate plating method further comprising, when the detected current value has decreased to a predetermined value or lower with respect to the initial current value, performing the first electroplating process, the plating accelerator removal process, and then the constant-electric-potential second electroplating process again. 
 
     
     
       6. The substrate plating method according to  claim 1 , wherein the first electroplating process is performed at a constant current with a current density in a range of 10 A/m 2  to 100 A/m 2 . 
     
     
       7. The substrate plating method according to  claim 1 , wherein the plating accelerator removal process is performed while stirring the second electrolytic solution. 
     
     
       8. The substrate plating method according to  claim 1 , wherein the first electroplating process, the plating accelerator removal process, and the second electroplating process are repeated. 
     
     
       9. The substrate plating method according to  claim 1 , further comprising cleaning of the substrate between the first electroplating process, the plating accelerator removal process, and the second electroplating process. 
     
     
       10. The substrate plating method according to  claim 1 , wherein the second electrolytic solution has a chloride ion concentration higher than a chloride ion concentration of the first electrolytic solution. 
     
     
       11. The substrate plating method according to  claim 10 , wherein the second electrolytic solution has a chloride ion concentration in a range of 1 mg/L to 100 mg/L.